duolingo app iphone

[andrea-9876]

My duolingo iphone app worked fine when i got it first, now for the last few days it won't let me sign in - it tells me I have a wrong username or password. This isn't the case as I have repeatedly signed into the web version. I have tried changing my password, deleted the app, reinstalled it but still the same problem!! It's making me mad. Any help?? Please?!